APES Unit 3 populations

Realized niche

range of biotic & abiotic conditions where a species actually lives

Niche generalist

species that live under a wide range of conditions ex: mule deer, racoons

Niche specialists

species that live only in specific habitats (vulnerable to extinction) ex: giant panda

K-selected species

a species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity…limited by carrying capacity ex: elephant

R-selected species

high intrinsic growth rate, overshoots and dies offs, small organisms, reproduce frequently ex: mosquitos

Growth rate

the number of offspring an individual can produce in a given time period, minus the deaths of the individual or offspring during the same period

Intrinsic growth rate (r)

under ideal conditions, with unlimited resources, the maximum potential for growth

J-shaped curve

exponential growth, intrinsic growth rate, open system, unlimited resources

Carrying capacity (k)

the limit of how many populations the environment can sustain

Logistic growth

when a population whose growth is initially exponential, but slows as the population approaches the carrying capacity

S-shaped curve

shape of logistic growth

Overshoot

when a population becomes larger than the environment’s carrying capacity

Die Off

a rapid decline in population due to death

Population ecology

the study of factors that cause populations to increase or decrease

Density-dependent factors

the size of the population will influence an individual’s probability of survival ex: water, food, nest size

Density-independent factors

the size of the population has no effect on the individual’s probability of survival ex: tornado, hurricane, flood, temperature

Population size (N)

total number of individuals in define areas at a given time

Population sex ratio

ratio of males to females, not always a 50/50 ratio, 1:1 maximizes population

Population age structure

how many individuals fit into age categories, predicts future growth

Population distribution

how individuals are distributed with respect to one another

Random distribution

no pattern to the location of individuals

Uniform distribution

toxic plants, desert nesting birds

Clumped distribution

schooling fish

Limiting resource

resource that a population cannot live without and which occurs in quantities lower than the population would require to increase in size ex: N & P for plants

Largest population

India (1.48 bill), China (1.41 bill), US (349.7 mil)

Factors affecting birth and death rates

access to education (especially women)

healthcare

family planning

nutrition

Immigration

the movement of people into a country

Emigration

the movement of people out of a country

Net migration rate

the difference between immigration and emigration in a given year per 1000 people in the country

Natality

the number of people added into a country (or globally) by being born

Mortality

the number of people removed from a country (or globally) by dying

Crude birth rate (CBR)

the number of births per 1000 individuals per year

Crude death rate (CDR)

the number of deaths per 1000 individuals per year

Total fertility rate (TFR)

an estimate of the average number of children that each

Replacement level fertility

the total fertility rate required to offset the average number of deaths in a population and for the current population size to remain stable

Developing Nations

TFR above 2.1 ex: Uganda - 4.5

Developed Nations

TFR at or below 2.1 ex: UK - 1.6

Societal factors influencing TFR

age of 1st pregnancy

educational opportunities

family planning

governmental policies

infant mortality and access to healthcare

nutrition

Life expectancy

the average number of years that an infant in a particular year in a particular country can be expected to live, given the current average life span and death rate of that country

Infant mortality rate

the number of deaths of children under 1 year of age per 1000 live births

Child mortality rate

the number of deaths of children under age 5 per 1000 live births (infant gets included into child)

Age structure diagrams (population pyramids)

visual representations of age structure within a country for males and females

The demographic transition

the theory of the demographic transition is the theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth

Phase 1 / Pre Industrial Stage

slow population growth because there are high birth rates and high death rates which offset each other ex: Chad

Phase 2 / Transitional stage

rapid population growth because birth rates remain high but death rates decline due to better sanitation, clean drinking water, increased access to food and goods, and access to health care- including childhood vaccinations ex: India

Phase 3 / Industrial stage

stable population growth as the economy and educational system improves and people have fewer children ex: USA

Phase 4 / Post Industrial stage

because population growth because the relatively high level of affluence and economic development encourage women to delay having children ex: Italy

Family planning

the regulation of the number or spacing of offspring through the use of birth control